Quantum anomalous Hall insulator of composite fermions in twisted bilayer graphene

TL;DR

This paper theoretically demonstrates that twisted bilayer graphene can host a quantum anomalous Hall insulator of composite fermions, leveraging its moiré pattern and tunable potential, providing a new platform for exploring topological states.

Contribution

It introduces a theoretical framework for realizing QAHI of composite fermions in TBG, highlighting the role of moiré patterns and orbital magnetic susceptibility.

Findings

Moiré pattern in TBG enables a tunable periodic potential for CFs.

Phase diagram of QAHI states depends on experimental parameters.

Orbital magnetic susceptibility of CFs is crucial for topological properties.

Abstract

Abstract We theoretically study the realization of quantum anomalous Hall insulator (QAHI) of composite fermions (CFs) in the twisted bilayer graphene (TBG) system. We show that the moir\'e pattern in TBG is not only able to provide a commensurate moir\'e superlattice, but also a tunable effective periodic potential necessary for the realization, without the need of imposing an additional superstructure as in the conventional GaAs system. These make the TBG an ideal platform for realizing the QAHI of CFs. We establish the phase diagram with respect to tunable experimental parameters based on the Dirac CF theory. We find that the topological property of the system depends critically on the orbital magnetic susceptibility of CFs, which is not specified in the pristine Dirac CF theory. The experimental realization of QAHI of CFs would be helpful for unveiling the magnetic property of CFs and clarifying the issue.